The Dunbeath Water - Neil Gunn's 'Highland River'

The tongue of land between the streams rose abruptly to a promontory on which the ruins of a broch indicated sufficiently the nature of the structure. A round circular building, at one time probably about fifty to sixty feet high, it still has the single small doorway through its twelve-foot-thick wall, and the chamber in the wall on the right hand for guarding the doorway. Inside, too, one may enter a beehive room also in the wall, almost opposite the doorway... The great wall had tumbled in ruins, but this little room was as it had been in the days of Christ...
When Kenn and Beel crept in through the little door and stood in the gloom, they were vaguely disturbed as if the little door telescoped backwards into a remoteness that at any moment might come up at their elbow.

—Neil M Gunn, Highland River